Leptospirosis is the most widespread neglected zoonotic disease in the world. It affects vulnerable populations such as rural subsistence farmers and urban slum dwellers. Urban epidemics are reported in cities in developing countries and will likely increase as the world?s slum population doubles to 2 billion by 2030. An unexpected outbreak was reported in New York City recently and climate change may account for its re-emerging status. A recent review of published cases estimated that leptospirosis causes ~1 million cases a year resulting in ~5-10% death rate. The gold standard for serodiagnosis of Leptospirosis is the MAT assay, which is 100 years old. MAT cannot be used for rapid case identification since it requires analysis of paired serum (acute and convalescent) in a reference laboratory with highly trained personnel and expensive equipment. Thus, MAT is rarely performed routinely even by diagnostic laboratories. Currently, there are no rapid quantitative assays on the market for serodiagnosis of Leptospirosis. In this Phase I SBIR, we propose two specific aims to develop a new diagnostic testing device for detection of antibodies against multiple L. interrogans antigens at the Point-of-Care. This low-cost portable device is a quantitative rapid assay that can perform POC testing as accurately as a laboratory ELISA. The test will be inexpensive (about 10 cents in material) and can be performed in 20 minutes, allowing for early diagnosis of Leptospirosis and treatment in the first visit to the doctor?s office. The technology can be adapted to a smartphone-based reader in a subsequent Phase II application to allow for serodiagnosis in remote field locations.